The present invention relates to an electrolyte for an electrolytic capacitor and a capacitor formed therewith.
There has been an ongoing demand for ever smaller electrical components to support the continual drive to smaller devices. Of particular interest for the present invention is the demand for smaller, yet higher capacitance density, electrolytic capacitors. This demand has exhausted the current technical capabilities thereby requiring further advances in the art. Such an advance is provided herein.
Electrolytic capacitors, particularly tantalum-based capacitors, have been prepared utilizing aqueous solutions of ethylene glycol with ionogens such as acetic acid and phosphoric acid and ammonium acetate. Capacitors of this type are exemplified in U.S. Pat. No. 6,219,222. While these capacitors have historically fulfilled many of the necessary requirements they are deficient. Other solvents are desirable that eliminate sparking and that improve resistance to electrochemical degradation.
Yet another problem associated with prior art working electrodes is the degradation of the electrolyte that occurs at low temperature. Prior art capacitors must be maintained at temperatures above the freezing point of the electrolyte. This has led away from the use of aqueous electrolytes while relinquishing the superior solubility properties and charge carrying properties of water. Water is greatly preferred over organic solvents yet the propensity for freezing is detrimental to its use as a solvent for working electrolytes.
The present invention is directed to an aqueous electrolyte, and capacitor containing the electrolyte, which mitigates the deficiencies of the prior art.